An existing high-efficiency low-energy-consumption Ethernet standard implemented by an electric port auto-negotiation mechanism-based Institute of Electrical and Electronic Engineers (IEEE) 802.3az protocol is called Energy Efficient Ethernet (EEE). EEE includes cooperative work of a Media Access Control (MAC) chip and a Physical (PHY) chip, and the PHY chip enters a low power mode when an online load is lighter. The low power mode may independently run in a receiving direction and a transmission direction, and a part of temporarily unnecessary functional circuits are switched off to fulfil the aim of reducing power consumption.
In order to implement EEE without influence on a basic message forwarding function of the Ethernet, it is necessary to keep a port entering a low power mode and a link state of an opposite port unchanged. Moreover, when the port enters or quits the low power mode, message loss or damage is not allowed.